Which of the following is a primary concern for vessels anchored in a traffic separation scheme?

The primary concern for vessels anchored in a traffic separation scheme is maintaining visibility to other vessels. In such areas, where ships are navigating closely together, it is crucial for anchored vessels to be easily seen by others to prevent collisions and ensure safe navigation. Visibility is essential for other vessels to recognize anchored ships and maintain safe distances, especially in busy shipping lanes where the traffic flow can be heavy.

When vessels are properly visible, it helps reduce the risk of accidents by allowing other mariners to make informed navigational decisions. Additionally, this visibility often involves ensuring that lights and shapes are displayed correctly according to the International Regulations for Preventing Collisions at Sea (COLREGs), which enhances safety.

The other options, while related to navigation and operational concerns, do not directly address the primary safety issue of visibility in traffic separation schemes. Providing communication to shoreside facilities, conserving fuel supplies, and crew scheduling are important but secondary in the context of immediate navigational safety within high-traffic areas.